RU2666072C2 - Electric motor vehicle control device and electric motor vehicle control method - Google Patents

Abstract

FIELD: machine building.SUBSTANCE: group of inventions relates to the control of the traction system of vehicles with electric traction. Electric motor control device for the electric motor vehicle comprises a module for setting the values of the electric motor torque command and the electric motor control module. Command module for setting the values of the electric motor torque command is configured to set the value of the first target driving torque based on the vehicle information as the torque command value of the electric motor and set the value of the second target torque to stop the vehicle and maintain the stop state. Second target torque is set when the speed parameter becomes equal to or less than a predetermined value. Electric motor control module stops the vehicle and maintains the stop state by means of the value of the second target torque. Control method for an electromotive vehicle is also claimed.EFFECT: reduced vibration in the longitudinal direction when the vehicle stops.16 cl, 14 dwg

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a control device for an electric motor vehicle and to a control method for an electric motor vehicle.

State of the art

[0002] Traditionally, a regenerative brake control device for electric vehicles is known, which comprises a setting means allowing arbitrary setting of the regenerative braking force of the electric motor, and performs recovery of the electric motor by means of the regenerative braking force set by the setting means (see JP8-79907A).

SUMMARY OF THE INVENTION

[0003] However, if the regenerative braking force set by the setting means is large, there is a problem of vibration generation in the longitudinal direction of the vehicle body when the electric vehicle is decelerated by the set regenerative braking force and the speed becomes zero.

[0004] The present invention is directed to the provision of technology to suppress the generation of vibration in the longitudinal direction of a vehicle body when the electric vehicle is stopped due to regenerative braking force.

[0005] An electric vehicle control device according to an embodiment is a control device for an electric motor vehicle using the electric motor 4 as a driving source, and is configured to decelerate by the regenerative braking force of the electric motor 4, to calculate the value of the first target torque based on the information vehicle and calculate the value of the second target torque, which converges to zero with decreasing param speed, proportional to the speed of the electric motor vehicle. If it is determined that the vehicle has not reached the moment immediately before stopping, the value of the first target torque is set as the value of the torque control command of the electric motor. If it is determined that the vehicle should stop soon, the value of the second target torque is set as the value of the torque control command of the electric motor. The electric motor 4 is controlled based on the set value of the torque control command of the electric motor.

[0006] Embodiments of the present invention and advantages of the present invention together with the accompanying drawings are described in detail below.

Brief Description of the Drawings

[0007] FIG. 1 is a block diagram showing a basic configuration of an electric vehicle with a control device for an electric motor vehicle in one embodiment,

FIG. 2 is a flowchart showing a process flow of an electric motor current control process performed by an electric motor controller,

FIG. 3 is a graph showing an example of a table of torques depending on the opening of the accelerator pedal,

FIG. 4 is a flowchart showing in detail a method for setting a value Tm1 * of a first target torque,

FIG. 5 is a block diagram showing a detailed configuration of a disturbing torque evaluation unit,

FIG. 6 is a block diagram showing a detailed configuration of a disturbance correction torque setting module,

FIG. 7 is a graph showing an example of a table setting the relationship of the estimated value Td of the disturbing torque and the gradient correction torque Td5,

FIG. 8 shows an example of a table setting the relationship of the rotation speed ωm of the electric motor and the correction gain Kω based on the speed,

FIG. 9 is a diagram simulating a transmission system for transmitting a vehicle driving force,

FIG. 10 is a flowchart for implementing a stop control process,

FIG. 11 is a diagram showing a method for calculating feedback torque Tω based on a rotational speed of an electric motor based on a specific rotational speed ωm of an electric motor,

FIG. 12 is a diagram showing control results for stopping to stop an electric motor vehicle on a road going uphill,

FIG. 13 is a diagram showing control results for stopping to stop an electric motor vehicle on a downhill road, and

FIG. 14 is a flowchart for implementing a stop control process in the case of setting the feedback torque Tω based on the rotation speed of the electric motor as the value Tm2 * of the second target torque.

Detailed Description of Embodiments

[0008] FIG. 1 is a block diagram showing a basic configuration of an electric vehicle with a control device for an electric motor vehicle in one embodiment. The control device for an electric motor vehicle of the present invention includes an electric motor as part or all of a vehicle driving source and is applicable to an electric motor vehicle capable of being driven by a driving force of an electric motor. Electric motor vehicles include not only electric vehicles, but also hybrid vehicles and fuel cell vehicles. In particular, the control device for an electric motor vehicle in the present embodiment can be applied to a vehicle capable of controlling acceleration / deceleration and stop of the vehicle only by the operation of depressing the accelerator pedal. In this vehicle, the driver depresses the accelerator pedal during acceleration and decreases or nullifies the amount of accelerator pedal depressed during deceleration or during stop.

[0009] The electric motor controller 2 has signals indicative of the state of the vehicle, such as the vehicle speed V, the accelerator pedal AP opening, the rotor phase α of the electric motor 4 (three-phase AC electric motor) and the currents iu, iv and iw of the electric motor 4 inputted thereto in the form of digital signals, and generates PWM signals for controlling the electric motor 4 based on the input signals. Additionally, the motor controller 2 generates a drive signal for the inverter 3 in accordance with the generated PWM signals.

[0010] The inverter 3 includes, for example, two switching elements (for example, power semiconductor elements such as IGBTs or MOSFETs) for each phase, converts the direct current supplied from the battery 1 to alternating current by turning the switching on and off elements in accordance with the drive signal, and causes the required current to flow into the electric motor 4.

[0011] The electric motor 4 generates a driving force by means of an alternating current supplied from the inverter 3, and transmits the driving force to the left and right drive wheels 9a, 9b through the gearbox 5 and the drive shaft 8. Further, during rotation according to the rotation of the drive wheels 9a, 9b in while the vehicle is in motion, the electric motor 4 generates a regenerative driving force, thereby collecting the kinetic energy of the vehicle as electricity. In this case, the inverter 3 converts the alternating current generated during operation in the regenerative mode of the electric motor 4 into direct current and supplies it to the battery 1.

[0012] The current sensor 7 detects three-phase alternating currents iu, iv and iw flowing in the electric motor 4. However, since the sum of the three-phase alternating currents is 0, the currents of two arbitrary phases can be determined, and the current of the remaining one phase can be obtained by calculation.

[0013] The rotation sensor 6, for example, is a circular position sensor or a position sensor and determines the phase α of the rotor of the electric motor 4.

[0014] FIG. 2 is a flowchart showing a sequence of operations of an electric motor current control process performed by an electric motor controller 2.

[0015] In step S201, signals are input indicative of the state of the vehicle. Here, the vehicle speed V (km / h), the opening of the AP accelerator pedal (%), the phase α of the rotor (rad) of the electric motor 4, the speed Nm of rotation (rpm) of the electric motor 4, three-phase alternating currents iu, iv and iw are introduced flowing in the electric motor 4, and the value of Vdc constant voltage (V) between the battery 1 and the inverter 3.

[0016] Vehicle speed V (km / h) is obtained through an un illustrated vehicle speed sensor or through communication from another controller. Alternatively, the vehicle speed v (m / s) is obtained by multiplying the mechanical angular velocity ωm of the rotor by the dynamic radius R of the tire and dividing the product by the final drive gear ratio and then multiplying by 3600/1000 to convert the units of measurement, thereby obtaining the speed V vehicle (km / h).

[0017] Opening the accelerator pedal AP (%) is obtained from an un illustrated accelerator pedal opening sensor or via communication from another controller, such as an un illustrated vehicle controller.

[0018] The phase α of the rotor (rad) of the electric motor 4 is obtained from the rotation sensor 6. The rotational speed Nm (r / min) of the electric motor 4 is obtained by dividing the angular velocity ω of the rotor (electric angle) by the number P of the pole pair of the electric motor 4 to obtain the rotational speed ωm of the electric motor (rad / s), which is the mechanical angular speed of the electric motor 4, and multiplying the obtained rotation speed ωm of the electric motor by 60 / (2π). The angular velocity ω of the rotor is obtained by differentiating the phase α of the rotor.

[0019] The currents iu, iv and iw (a) flowing in the electric motor 4 are obtained from the current sensor 7.

[0020] The constant voltage (V) Vdc value is obtained from a voltage sensor (not shown) provided in the DC power line between the battery 1 and the inverter 3, or a voltage value transmitted from the battery controller (not shown).

[0021] In step S202, a value Tm1 * of the first target torque is set. In particular, the target value Tm0 * of the torque table (the base value of the target torque) is first set based on the opening of the accelerator pedal AP and the rotational speed ωm of the electric motor input in step S201 by referring to the torque table depending on the opening of the accelerator shown in FIG. 3. Then, an estimated disturbance torque value Td is obtained, which is described below, and a disturbance correction torque Td * is obtained based on the estimated disturbance torque value Td. Then, the value Tm1 * of the first target torque is set by summing the target value T0 * of the torque table and the disturbance correction torque Td *.

[0022] In step S203, a stop control process is performed in order to perform such control that the electric motor vehicle is stopped. In particular, the moment immediately before the stop of the electric motor vehicle is estimated, the value Tm1 * of the first target torque calculated in step S202 is set as the value Tm * of the torque control command of the electric motor until just before the stop, and the value Tm2 * of the second target torque , which converges to the estimated value Td of the disturbing torque with a decrease in the rotation speed of the electric motor, is set as the value Tm * of the torque control command om the motor after the time immediately before the stop. This Tm2 * value of the second target torque is the positive torque on the road going uphill, the negative torque on the road going downhill, and almost zero on a flat road. Thus, the stopping state of the vehicle can be maintained regardless of the gradient of the road surface, as described below. The following describes the details of the stop control process.

[0023] In step S204, the target d-axis current value id * and the q-axis current target value iq * are obtained based on the target motor torque value Tm * calculated in step S203, the rotation speed ωm of the electric motor, and the constant voltage value Vdc. For example, a table specifying the relationship between the target value of the d-axis current and the target value of the q-axis current with the value of the torque control command, the rotational speed of the electric motor and the constant voltage value is prepared in advance, and the target value id * of the current of the d-axis and the target value iq * q-axis currents are obtained by referring to this table.

[0024] In step S205, the current control is performed so as to compare the d-axis current id and the d-axis current iq with the target d-axis current id * and the q-axis current target iq * obtained in step S204 . To this end, the d-axis current id and the d-axis current iq are first obtained based on the values iu, iv and iw of the three-phase alternating current and the phase α of the rotor of the electric motor 4 inputted in step S201. Then, the values vd, vq of the d-axis and q-axis voltage control commands are calculated from deviations between the id *, iq * values of the d-axis and q-axis current control commands and the id, iq currents of the d-axis and q-axis. It should be noted that the noise immunity voltage necessary to balance the interference voltage between the orthogonal axes of the d-q coordinates can be added to the calculated values of the d-axis and q-axis voltage control commands vd, vq.

[0025] After this, the values vu, vv and vw of the three-phase AC voltage control commands are obtained from the values of vd, vq of the d-axis and q-axis voltage control commands and the phase α of the rotor of the electric motor 4. Then, the PWM signals tu (%), tv ( %) and tw (%) are obtained from the obtained values of vu, vv and vw of the three-phase alternating voltage control commands and the constant voltage value Vdc. By opening and closing the switching elements of the inverter 3 by means of the PWM signals tu, tv and tw obtained in this way, the electric motor 4 can be driven with the required torque instructed by the torque control value Tm *.

[0026] The process in step S202 of FIG. 2, i.e. a method for setting the value Tm1 * of the first target torque using FIG. four.

The torque table target setting unit 401 sets the target table Tm0 * of the torque table based on the opening of the accelerator pedal AP and the rotation speed ωm of the electric motor by referring to the torque table depending on the opening of the accelerator pedal shown in FIG. 3.

[0028] The disturbing torque estimation unit 402 obtains an estimated disturbing torque value Td based on the value Tm * of the torque control command of the electric motor and the rotation speed ωm of the electric motor.

[0029] FIG. 5 is a block diagram showing a detailed configuration of a disturbing torque estimator 402. The disturbing torque evaluation unit 402 includes a control unit 501, a control unit 502, a subtraction unit 503, and a control unit 504.

[0030] The control unit 501 acts as a filter having a transmission characteristic H (s) / Gp (s), and calculates a first estimated value of the electric motor torque by filtering the rotation speed ωm of the electric motor input thereto. Gp (s) is a characteristic of the transmission from the electric motor torque Tm to the electric motor rotation speed ωm and is described in detail below. H (s) is a low-pass filter having such a transmission characteristic that the difference between its degree of the denominator and the degree of the numerator is not less than the difference between the degree of the denominator and the degree of the numerator of the model Gr (s).

[0031] The control unit 502 acts as a low-pass filter having a transmission characteristic H (s), and calculates a second estimated torque value of the electric motor by filtering the value Tm * of the torque control command of the electric motor input thereto.

[0032] The subtraction unit 503 calculates the estimated value Td of the disturbing torque by subtracting the first estimated value of the torque of the electric motor from the second estimated value of the torque of the electric motor.

[0033] In the present embodiment, the estimated disturbance torque value Td is calculated by filtering the deviation between the second estimated torque value of the electric motor and the first estimated torque value of the electric motor by the control unit 504. The control unit 504 acts as a filter having a transmission characteristic Hz (s), and calculates an estimated disturbance torque value Td by filtering a deviation between the second estimated electric motor torque value and the first estimated electric motor torque value input thereto. The following describes in detail Hz (s).

[0034] The disturbance correction torque setting module 403 of FIG. 4 receives the disturbance correction torque Td * based on the estimated disturbance torque value Td calculated by the disturbance torque estimator 402.

[0035] FIG. 6 is a block diagram showing a detailed configuration of a disturbance correction torque setting unit 403. The perturbation correction torque setting module 403 includes a correction correction torque calculation module 601, an abrupt correction correction processor 602, a descent correction torque calculation module 603, an abrupt correction correction processor 604, a gradient determination module 605, and a correction torque setting processor 606 moment based on speed.

[0036] The lifting corrective torque calculation module 601 calculates the corrective lifting torque Td1 by multiplying the estimated disturbance torque value Td by a predetermined corrective gain Kup.

[0037] The steep lift correction processor 602 applies the constraint setting processing to the correction torque Td1 when lifting based on the value of the torque control command of the torque table electric motor depending on the opening of the accelerator pedal shown in FIG. 3 when "opening the accelerator pedal = 0/4 (fully closed)", and calculates the limiting torque Td2 when lifting after processing the job restrictions.

[0038] The descent correction torque calculation unit 603 calculates the descent correction torque Td3 by multiplying the estimated perturbation torque value Td by the predetermined descent correction gain Kdown.

[0039] The steep hill correction processor 604 calculates the descent limiting torque Td4 to set the vehicle deceleration to be constant when the absolute value of the estimated perturbation torque value Td is not less than a predetermined value, for example, on a steep slope. In particular, the vehicle deceleration on a steep slope is indicated, and the required limiting torque Td4 during descent is calculated from the torque command value of the electric motor of the torque table depending on the opening of the accelerator pedal shown in FIG. 3 when "opening the accelerator pedal = 0/4 (fully closed)", and the estimated value Td of the disturbing torque.

[0040] The gradient determination module 605 determines the road surface gradient based on the sign of the estimated value Td of the disturbing torque and sets the limiting torque Td2 when lifting as the gradient correction torque Td5 on the slope of the gradient (estimated value Td of the disturbing torque> 0) when setting limiting torque Td4 during descent as torque Td5 gradient correction on the slope of the descent (estimated value Td disturbing torque <0).

[0041] It should be noted that a table setting the relationship of the estimated value Td of the disturbing torque and the gradient correction torque Td5 can be prepared in advance, and the gradient correction torque Td5 can be calculated based on the estimated value Td of the disturbing torque by referring to this table .

[0042] FIG. 7 is a graph showing an example of a table setting the relationship of the estimated value Td of the disturbing torque and the gradient correction torque Td5. In the case of a steep climb road surface, i.e. if the estimated value Td of the disturbing torque is not less than a predetermined value Td1, the gradient correction torque Td5 is set to a predetermined upper limit value. Additionally, in the case of a road going uphill, which is not a steep slope, i.e. if the estimated value Td of the disturbing torque exceeds 0 and is lower than the predetermined value Td1, the gradient correction torque Td5 is set to a smaller value (however, Td5> 0) as the estimated value Td of the disturbing torque becomes smaller. In the case of a road going downhill, which is not a steep slope, i.e. if the estimated value Td of the disturbing torque is less than 0 and greater than the predetermined value Td2, the gradient correction torque is set to a smaller value (however, Td5 <0) as the estimated value Td of the disturbing torque becomes smaller. In the case of a steep descent road surface, i.e. if the estimated value Td of the disturbing torque does not exceed a predetermined value Td2, the gradient correction torque is set to a smaller value (however, Td5 <0) as the estimated value Td of the disturbing torque becomes smaller. However, in the case of a steep slope, the gradient correction torque Td5 is set to an even lower value as the estimated value of the disturbing torque becomes smaller compared to a downhill road that is not a steep slope.

[0043] The corrective torque setting processor 606 based on the speed of FIG. 6 obtains a correction gain Kω based on the speed based on the rotation speed ωm of the electric motor by referring to a table setting the relationship of the rotation speed ωm of the electric motor and the correction gain Kω based on the speed, and calculates the disturbance correction torque Td * by multiplying the gradient correction torque Td5 by the correction Kω gain based on speed.

[0044] FIG. 8 shows an example of a table setting the relationship of the rotational speed ωm of the electric motor and the correction gain Kω based on the speed. The velocity-based correction gain Kω is set to 1 in the low speed region in which the electric motor rotation speed ωm is lower than the predetermined rotation speed ωm and set to 0 in the high speed region in which the electric motor rotation speed ωm is not lower than the predetermined rotation speed ωm2 ( ω1 <ω2). Thus, the gradient correction torque Td5 is output as the disturbance correction torque Td * in the low velocity region and is set to 0 in the high velocity region. Additionally, in the middle-speed region, in which the electric motor rotation speed ωm is not lower than the predetermined rotation speed ωm1 and lower than the predetermined rotation speed ωm2, the speed-based correction gain is set so that it becomes smaller as the rotation speed ωm increases electric motor.

[0045] Referring again to FIG. 4, the description continues. The adder 404 calculates the first target torque value Tm1 * by summing the target torque table value Tm0 * specified by the torque table target setting unit 401 and the perturbation correction torque Td * specified by the perturbation correction torque setting unit 403.

[0046] Since the deceleration until the moment immediately before stopping has been estimated can be controlled by calculating the first target torque value Tm1 * by the above method, a decrease in the magnitude of the change relative to the deceleration to deceleration can be suppressed when the torque command value Tm * the torque of the electric motor converges to the estimated value Td of the disturbing torque in order to stop the vehicle, and the driving feel can be improved lion.

[0047] Then, before the stop control process in step S203 is described, the transmission characteristic Gp (s) from the electric motor torque Tm to the electric motor rotation speed ωm is described in the control device for the electric motor vehicle in the present embodiment.

[0048] FIG. 9 is a diagram simulating a transmission system for transmitting a vehicle driving force, and each parameter in FIG. 9 is explained as follows.

J _m - inertia of the electric motor

J _w - inertia of the drive wheels

M - vehicle weight

K _d - torsional stiffness of the drive system

K _t - coefficient connecting friction between tires and road surface

N - total gear ratio

r - tire load radius

ω _m - angular speed of the electric motor

T _m - value of the target torque

T _d - drive wheel torque

F - force applied to the vehicle

V - vehicle speed

ω _w is the angular velocity of the drive wheels

[0049] The following equations of motion can be derived from FIG. 9. However, an asterisk (*), appended to the upper right corner of the reference symbol in equations (1) to (3), indicates the time derivative.

equation 1

...(1)

...(one)

equation 2

...(2)

... (2)

equation 3

...(3)

... (3)

equation 4

...(4)

...(four)

equation 5

...(5)

...(5)

[0050] The transmission characteristic Gp (s) from the target torque value Tm to the rotation speed ωm of the electric motor for the electric motor 4, obtained based on the equations of motion (1) to (5), is expressed by the following equation (6).

equation 6

...(6)

... (6)

[0051] Here, each parameter in equation (6) is expressed by the following equations (7).

equation 7

...(7)

... (7)

[0052] The poles and zero point of the transfer function shown in equation (6) can be approximated to the transfer function of the next equation (8), and one pole and one zero point indicate values that are extremely close to each other. This is equivalent to the fact that α and β of the following equation (8) indicate values extremely close to each other.

equation 8

...(8)

...(8)

[0053] Accordingly, by performing the cancellation of zeros and poles (approximations for α = β) in equation (8), Gp (s) constitutes the transmission characteristic (second order) / (third order), as shown in the following equation (9).

equation 9

...(9)

...(9)

[0054] After that, details of the stop control process performed in step S203 of FIG. 2. FIG. 10 is a flowchart for implementing a stop control process.

[0055] The feedback torque setting unit 1001 based on the rotation speed of the electric motor calculates the feedback torque Tω based on the rotation speed of the electric motor (hereinafter, referred to as the “feedback torque based on the rotation speed of the electric motor”) based on the determined speed ωm rotation of the electric motor.

[0056] FIG. 11 is a diagram showing a method for calculating feedback torque Tω based on a rotational speed of an electric motor based on a determined rotational speed ωm of an electric motor. The feedback torque setting module 1001 based on the rotational speed of the electric motor includes a multiplier 1101 and calculates the feedback torque Tω based on the rotational speed of the electric motor by multiplying the rotational speed ωm of the electric motor by the gain Kvref. However, Kvref is a negative value (with a minus sign) necessary to stop the electric vehicle immediately before the electric vehicle stops, and is set appropriately, for example, from experimental data and the like. The feedback torque Tω, based on the rotation speed of the electric motor, is set as the torque allowing a greater regenerative braking force to be achieved as the rotation speed ωm of the electric motor increases.

[0057] It should be noted that although the feedback torque setting module 1001 based on the rotation speed of the electric motor is described for calculating the feedback torque Tω based on the rotation speed of the electric motor by multiplying the rotation speed ωm of the electric motor by the gain Kvref, the feedback torque Tω based on the rotational speed of the electric motor can be calculated using a table of regenerative torques that defines the regenerative torque relative to the rotation speed ωm of the electric motor, the rate of decline of the table preserving speed decay rate ωm rotation motor in advance, etc.

[0058] Referring again to FIG. 10, the description continues. The disturbing torque estimator 1002 calculates the estimated disturbance torque value Td based on the determined rotation speed ωm of the electric motor and the torque command value Tm * of the electric motor. The configuration of the disturbing torque estimator 1002 is identical to the configuration of the disturbing torque estimator 402 of FIG. 4, i.e. the configuration shown in FIG. 5.

[0059] Here, the transmission characteristic Hz (s) of the control unit 504 of FIG. 5. The following equation (10) is obtained by rewriting equation (9). ζ _z , ω _z , ζ _p and ω _p in equation (10) are expressed by equations (11).

equation 10

...(10)

...(10)

equation 11

...(11)

...(eleven)

[0060] From the above, Hz (s) is expressed by the following equation (12). However, ζ _c > ζ _z . Additionally, ζ _c > 1, in order to improve the effect of suppressing vibration in the environment during deceleration associated with transmission play.

equation 12

...(12)

...(12)

[0061] It should be noted that although the disturbing torque is estimated by the disturbance observation module, as shown in FIG. 5, in the present embodiment, it can be estimated using a counter, such as a sensor of the longitudinal component G of the vehicle.

[0062] Here, air resistance, simulation error caused by varying the mass of the vehicle due to the number of passengers and the permissible load, tire roll resistance, resistance due to a gradient of a road surface, and the like. can be considered disturbances, but the disturbance factor that dominates just before the vehicle stops is resistance due to the gradient. Perturbation factors differ depending on driving conditions, but the perturbation factors described above can be jointly evaluated since the perturbing torque estimator 402 and the perturbative torque estimator 1002 calculate the estimated perturbation torque value Td based on the torque command value Tm * electric motor moment, electric motor rotation speed ωm and vehicle model Gp (s). This ensures the implementation of a smooth stop of the vehicle after deceleration in any state of movement.

[0063] Referring again to FIG. 10, the description continues. The adder 1003 calculates the second target torque value Tm2 * by summing the feedback torque Tω based on the rotation speed of the electric motor calculated by the feedback torque setting unit 1001 based on the rotation speed of the electric motor and the estimated value of the disturbing torque Td calculated on the basis of the module 1002 estimates of disturbing torques.

[0064] The torque comparison unit 1004 compares the absolute values of the first and second target torque values Tm1 *, Tm2 * and sets a larger target torque value as the torque control command value Tm * of the electric motor. The Tm2 * value of the second target torque is less than the Tm1 * value of the first target torque while the vehicle is in motion. When the vehicle decelerates and reaches a moment immediately before stopping (vehicle speed is not higher than the predetermined vehicle speed), the value Tm2 * of the second target torque becomes greater than the value Tm1 * of the first target torque. Thus, if the value Tm1 * of the first target torque exceeds the value Tm2 * of the second target torque, the torque comparing unit 1004 estimates that the moment just before stopping has not been reached, and sets the value of the torque control command Tm * of the electric motor to the value Tm1 * first target torque. Further, when the second target torque value Tm2 * becomes larger than the first target torque value Tm1 *, the torque comparison unit 1004 estimates that the vehicle should stop shortly and switches the electric motor torque command value Tm * from the value Tm1 * first target torque at Tm2 * second target torque. It should be noted that the Tm2 * value of the second target torque is the positive torque on the road going uphill and the negative torque on the road going downhill and converges almost to zero on a flat road to maintain the vehicle's stopping state.

[0065] FIG. 12 is a diagram showing control results for stopping to stop an electric motor vehicle on a road going uphill. FIG. 12 (a) shows the control result of a comparative example of a configuration in which the target torque table value Tm0 * is not corrected when calculating the first target torque value Tm1 * (perturbation torque evaluation unit 402 and perturbation correction torque setting module 403 of FIG. 4 absent), and FIG. 12 (b) shows a control result by a control device for an electric motor vehicle in the present embodiment, wherein the wheel speed, deceleration, and torque command value of the electric motor are sequentially shown from above.

[0066] FIG. 12 (a), the vehicle decelerates based on the target value Tm0 * of the torque table calculated based on the opening of the accelerator pedal and the rotation speed of the electric motor up to time t3.

[0067] At time t3, it is estimated that the vehicle will stop soon due to a decrease in the rotation speed ωm of the electric motor to a predetermined rotation speed regardless of the gradient of the road surface, and the value of the torque control command Tm * of the electric motor is switched from the value Tm1 * of the first target torque torque to the Tm2 * value of the second target torque. Thus, the value Tm * of the torque control command of the electric motor suddenly changes so that it coincides with the estimated value Td of the disturbing torque during t3-t5. Due to a sudden change in the Tm * value of the torque control command of the electric motor, the driver feels a jolt due to the difference in the torque levels and a sudden change in torque during the switching of the value of the torque control command of the electric motor. In particular, since the value of the torque control command of the electric motor is switched at the same rotation speed (vehicle speed) regardless of the gradient of the road surface, the change in the value of the torque control command of the electric motor is large on the road going uphill, and the driver is likely to feel a jolt due to a sudden change in torque.

[0068] After time t5, the wheel speed becomes 0, and the vehicle stop state is maintained.

[0069] FIG. 12 (b), the section up to time t0 is the high-velocity region of FIG. 8, and the perturbation correction torque Td * calculated by the perturbation correction torque setting unit 403 is 0. Thus, up to the time t0, the vehicle decelerates based on the target value Tm0 * of the torque table output from the target setting unit 401 torque table values.

[0070] The portion from time t0 to time t1 is a region of average speeds in FIG. 8. In this section, the perturbation correction torque Td * is calculated by multiplying the gradient correction torque Td5 obtained from the estimated perturbation torque value Td by the correction gain Kω based on the speed corresponding to the rotation speed ωm of the electric motor (corrective torque setting processor 606 6), and the value Tm1 * of the first target torque is calculated by summing the target value Tm0 * of the torque table, output th unit of the 401 target value setting table torque, and torque Td * perturbation correction. Then, the vehicle decelerates based on the calculated value Tm1 * of the first target torque.

[0071] The portion after t1 is the low velocity region of FIG. 8. In this section, the disturbance correction torque Td * calculated by the disturbance correction torque setting unit 403 of FIG. 4 is equal to the estimated disturbance torque value Td obtained by the disturbance torque estimation unit 402, and the first target torque value Tm1 * is calculated by summing the target torque table value Tm0 * of the torque table output from the torque specification table 401, and torque Td * disturbance correction. Then, the vehicle decelerates based on the calculated value Tm1 * of the first target torque.

[0072] At time t2, the second target torque value Tm2 * becomes larger than the first target torque value Tm1 *, it is estimated that the vehicle should stop soon, and the electric motor torque command value Tm * is switched from the first engine torque value Tm1 * target torque by the value Tm2 * of the second target torque. This switching time differs depending on the gradient of the road surface. Thus, the value Tm * of the torque control command of the electric motor smoothly changes so that it converges to the estimated value Td of the disturbing torque during t2-t5.

[0073] At time t5, the value of the torque control command Tm * of the electric motor asymptotically converges to the estimated value Td of the disturbing torque, and the rotation speed ωm of the electric motor asymptotically converges to zero. Thus, it is possible to smoothly stop the vehicle without vibration during acceleration. After time t5, the vehicle stop state is maintained.

[0074] In particular, according to the control device for an electric motor vehicle in the present embodiment, the disturbance correction torque Td * is calculated based on the estimated disturbance torque value, whether or not the vehicle will stop in the near future, is also evaluated based on the calculated torque Td * correction of disturbances, and the value Tm * of the torque control command of the electric motor is switched from the value Tm1 * of the first target torque to the value Tm2 * of the second th target torque. Thus, smooth deceleration and stopping of a vehicle, equivalent to smooth deceleration and stopping on flat roads, can also be realized on roads going uphill.

[0075] FIG. 13 is a diagram showing control results for stopping to stop an electric motor vehicle on a downhill road. FIG. 13 (a) shows the control result of a comparative example of a configuration in which the target torque table value Tm0 * is not corrected when calculating the first target torque value Tm1 * (perturbation torque evaluation unit 402 and perturbation correction torque setting module 403 of FIG. 4 absent), and FIG. 13 (b) shows a control result by a control device for an electric motor vehicle in the present embodiment, wherein the wheel speed, deceleration, and torque command value of the electric motor are sequentially shown from above.

[0076] In FIG. 13 (a), the vehicle decelerates based on the target value Tm0 * of the torque table calculated based on the opening of the accelerator pedal and the rotation speed of the electric motor up to time t3.

[0077] At time t3, it is estimated that the vehicle will stop shortly due to a decrease in the rotation speed ωm of the electric motor to a predetermined rotation speed regardless of the gradient of the road surface, and the value of the torque control command Tm * of the electric motor is switched from the value Tm1 * of the first target torque torque to the Tm2 * value of the second target torque. Thus, during t3-t6, the time until the vehicle stops, and the distance to the stop becomes large, and the driving sensation is worsened due to a slow change in torque, thereby smoothly stopping the vehicle. In particular, in the configuration of the comparative example, in which the value of the torque control command of the electric motor is switched to the same rotation speed (vehicle speed) regardless of the gradient of the road surface, the time until the value Tm * of the torque control command of the electric motor converges to the estimated the value Td of the disturbing torque becomes large, and the driving sensation worsens on the roads going downhill.

[0078] After time t6, the wheel speed becomes 0, and the stopping state of the vehicle is maintained.

[0079] FIG. 13 (b), the section up to time t0 is the high-velocity region of FIG. 8, and the perturbation correction torque Td * calculated by the perturbation correction torque setting unit 403 is 0. Thus, up to the time t0, the vehicle decelerates based on the target value Tm0 * of the torque table output from the target setting unit 401 torque table values.

[0080] The portion from time t0 to time t1 is a region of average speeds in FIG. 8. In this section, the perturbation correction torque Td * is calculated by multiplying the gradient correction torque Td5 obtained from the estimated perturbation torque value Td by the correction gain Kω based on the speed corresponding to the rotation speed ωm of the electric motor (corrective torque setting processor 606 6), and the value Tm1 * of the first target torque is calculated by summing the target value Tm0 * of the torque table, output th unit of the 401 target value setting table torque, and torque Td * perturbation correction. Then, the vehicle decelerates based on the calculated value Tm1 * of the first target torque.

[0081] The portion after t1 is the low velocity region of FIG. 8. In this section, the disturbance correction torque Td * calculated by the disturbance correction torque setting unit 403 of FIG. 4 is equal to the estimated disturbance torque value Td obtained by the disturbance torque estimation unit 402, and the first target torque value Tm1 * is calculated by summing the target torque table value Tm0 * of the torque table output from the torque specification table 401, and torque Td * disturbance correction. Then, the vehicle decelerates based on the calculated value Tm1 * of the first target torque.

[0082] At time t4, the second target torque value Tm2 * becomes larger than the first target torque value Tm1 *, it is estimated that the vehicle should stop soon, and the electric motor torque command value Tm * is switched from the first engine torque value Tm1 * target torque by the value Tm2 * of the second target torque. This switching time differs depending on the gradient of the road surface.

[0083] At time t5, the value Tm * of the torque control command of the electric motor asymptotically converges to the estimated value Td of the disturbing torque, and the rotation speed ωm of the electric motor asymptotically converges to zero. Thus, it is possible to smoothly stop the vehicle without vibration during acceleration. After time t5, the vehicle stop state is maintained.

[0084] In particular, according to the control device for an electric motor vehicle in the present embodiment, the disturbance correction torque Td * is calculated based on the estimated disturbance torque value and whether or not the vehicle will stop soon (switching time of the command value Tm * control the torque of the electric motor from the value Tm1 * of the first target torque to the value Tm2 * of the second target torque is determined), is also estimated taking into account the subtraction lennogo torque Td * perturbation correction. Thus, smooth deceleration and stopping of the vehicle, equivalent to smooth deceleration and stopping on flat roads, can also be implemented on roads going downhill.

[0085] Here, although the second target torque value Tm2 * is calculated by summing the feedback torque Tω based on the rotational speed of the electric motor and the estimated value of the disturbing torque Td in the above description, the feedback torque Tω based on the rotational speed of the motor can be set to as the value of Tm2 * of the second target torque. FIG. 14 is a flowchart for implementing a stop control process in the case of setting the feedback torque Tω based on the rotation speed of the electric motor as the value Tm2 * of the second target torque. In FIG. 14 constituting elements identical to the constituent elements shown in FIG. 10 are denoted by identical reference numerals. In this case, the estimated value Td of the disturbing torque is calculated as zero when calculating the value Tm1 * of the first target torque (Fig. 4).

[0086] Also, when setting the feedback torque Tω based on the rotational speed of the electric motor as the value Tm2 * of the second target torque, the value Tm * of the torque control command of the electric motor switches from the value Tm1 * of the first target torque to the value Tm2 * of the second target torque when the value Tm2 * of the second target torque becomes greater than the value Tm1 * of the first target torque, and it is estimated that the vehicle should stop at the nearest remy. At this time, the value of the torque control command Tm * of the electric motor tends to zero as the rotation speed ωm of the electric motor decreases, since the value Tm2 * of the second target torque is almost equal to the feedback torque Tω based on the rotation speed of the electric motor.

[0087] As described above, the control device for an electric motor vehicle in one embodiment is a control device for an electric motor vehicle using electric motor 4 as a driving source, and is configured to decelerate by the regenerative braking force of electric motor 4 and calculates a value Tm1 * of the first target torque based on the vehicle information and calculates the value Tm2 * of the second target torque one which converges to zero as the motor rotation speed ωm decreases. The value Tm1 * of the first target torque is set as the value Tm * of the torque control command of the electric motor when it is determined that the vehicle does not reach the moment immediately before stopping, and the value Tm2 * of the second target torque is set as the value Tm * of the torque control command the moment of the electric motor, when it is determined that the vehicle should stop in the near future. The electric motor 4 is controlled based on the set torque value Tm * of the torque control command of the electric motor. In particular, since the torque control command value Tm * of the electric motor is switched from the value Tm1 * of the first target torque to the value Tm2 * of the second target torque immediately before the vehicle stops after the vehicle decelerates based on the value Tm1 * of the first target torque, based on the vehicle information, a smooth stop of the vehicle after deceleration can be realized. This ensures the implementation of a smooth deceleration and stop of the vehicle without vibration when accelerating in the longitudinal direction on smooth roads. Additionally, since the vehicle can slow down to a stopping state of the vehicle even without using braking force by means of mechanical braking means, such as a foot brake, the regenerative operation of the electric motor 4 is also possible just before the vehicle stops, and energy consumption can be improved. In addition, since the acceleration / deceleration and stop of the vehicle can only be realized by the operation of depressing the accelerator pedal, it is not necessary to press the accelerator pedal and the brake pedal with the switch, and the load on the driver can be reduced.

[0088] If the vehicle is stopped using the brake pedal, a driver who is not used to driving presses the accelerator pedal too much so that vibrations are generated when accelerating in the longitudinal direction of the vehicle when the vehicle is stopped. Additionally, if an attempt is made to decelerate and stop the vehicle while constantly decelerating in the vehicle to realize acceleration / deceleration and stopping the vehicle only by pressing the accelerator pedal, the deceleration should increase to realize sufficient deceleration during deceleration. Thus, vibrations during acceleration are generated in the longitudinal direction of the vehicle when the vehicle is stopped. However, according to the control device for an electric motor vehicle in one embodiment, any driver can realize a smooth deceleration and stop of the vehicle only by the operation of depressing the accelerator pedal, as described above.

[0089] Further, according to a control device for an electric motor vehicle in one embodiment, it is determined that the vehicle does not reach the moment immediately before stopping if the value Tm1 * of the first target torque exceeds the value Tm2 * of the second target torque when determining the stop in the near future, if the value Tm2 * of the second target torque exceeds the value Tm1 * of the first target torque. Thus, the Tm * value of the torque control command of the electric motor can be switched from the Tm1 * value of the first target torque to the Tm2 * value of the second target torque without generating a difference in the torque levels immediately before the vehicle stops. Additionally, since the larger of the values Tm1 *, Tm2 * of the first and second target torque is set as the Tm * value of the torque control command of the electric motor, smooth deceleration can be realized without generating a difference in the levels of torque during switching the value of the target torque at any gradient .

[0090] In particular, according to a control device for an electric motor vehicle in one embodiment, an estimated value Td of the disturbing torque is obtained, and a value of the target torque that converges to the estimated value Td of the disturbing torque as the speed ωm decreases rotation of the electric motor is calculated as the value Tm2 * of the second target torque. Thus, regardless of whether it is a road going uphill, a road going downhill, or a flat road, a smooth deceleration without vibrations when accelerating in the longitudinal direction can be realized immediately before the vehicle stops, and the stopping state of the vehicle funds can be supported.

[0091] Since the estimated value Td of the disturbing torque is estimated as a positive value on the road going uphill and a negative value on the road going downhill, the vehicle can also stop smoothly on gradients, and the stopping state of the vehicle can be maintained without the need for foot the brakes. Additionally, since the estimated value Td of the disturbing torque is estimated to be zero on a flat road, the vehicle can stop smoothly, and the stopping state of the vehicle can be maintained without the need for a foot brake also on flat roads.

[0092] Further, since the first target torque value Tm1 * is calculated by calculating the torque table target value Tm0 * based on the vehicle information and correcting the calculated torque table target value Tm0 * based on the estimated torque disturbance value Td, deceleration to the moment immediately before stopping, it is determined and can be adjusted based on the estimated disturbance torque value Td. Thus, the magnitude of the change in torque from the value Tm * of the torque control command of the electric motor to the moment immediately before stopping can be suppressed by the estimated value Td of the perturbing torque to which the value of Tm * of the torque control command of the electric motor converges when the vehicle is stopped, and can improve driving sensation by suppressing shock due to a change in torque.

[0093] In particular, since the disturbance correction torque Td * is calculated by multiplying the estimated disturbance torque value Td by a predetermined gain (Kup, Kdown), and the first target torque value Tm1 * is calculated by summing the target torque table value Tm0 * and perturbation correction torque Td *, the first target torque value Tm1 * can be calculated by linearly correcting the target value Tm0 * of the torque table according to Wii with indignation.

[0094] Further, the disturbance correction torque Td * is calculated by multiplying the product of the estimated disturbance torque value Td and the predetermined gain (Kup, Kdown) by the correction gain Kω based on the speed corresponding to the rotational speed ωm of the electric motor and the correction gain Kω based on speed is 1 if the rotation speed ωm of the electric motor is lower than the first predetermined rotation speed ωm1, equal to 0 if the rotation speed ωm of the electric motor is higher than the second preliminarily a predetermined rotation speed ωm2 exceeding the first predetermined rotation speed ωm1 and equal to a value not less than 0 and not more than 1 and closer to 0 as the rotation speed ωm of the electric motor increases, if the rotation speed ωm of the electric motor is not lower than the first predefined rotation speed ωm1 and not higher than the second predetermined rotation speed ωm2. The disturbing torque at high speeds is mainly due to air resistance. The sensation of acceleration / deceleration in the high-speed region can be matched with the driving sensation by reducing the disturbance correction torque Td * as the rotation speed ωm of the electric motor increases.

[0095] The present invention is not limited to the one embodiment described above. For example, in the above description, the value Tm2 * of the second target torque is the value of the target torque, which converges to the estimated value Td of the disturbing torque with a decrease in the rotation speed ωm of the electric motor. However, since speed parameters, such as wheel speed, vehicle body speed, and drive shaft speed, are proportionally related to the speed of electric motor 4, the value Tm2 * of the second target torque can forcefully converge to the estimated value Td of the disturbing torque (or zero) with a decrease in the speed parameter proportional to the speed of rotation of the electric motor 4.

[0096] Although an embodiment of the present invention has been described above, the above embodiment is only one example of an application of the present invention and is not intended to limit the scope of the present invention to a specific configuration of the above described embodiment.

[0097] This application claims priority on the basis of patent application (Japan) 2014-003179, filed January 10, 2014 to the Patent Office (Japan), the contents of which are fully contained in this document by reference.

Claims (42)

1. A device for controlling an electric drive of an electric motor vehicle using an electric motor as a source of propulsion and configured to decelerate by means of a regenerative braking force of an electric motor, comprising: an electric motor torque command value setting unit configured to set a first target torque value for driving based on vehicle information as an electric motor torque command value before the speed parameter proportional to the speed of the electric motor vehicle becomes equal to or less than a predefined value, and set the value of the second target torque to stop the electric a motor vehicle and maintaining a vehicle stop state as a value of an electric motor torque control command when the speed parameter becomes equal to or less than a predetermined value; and an electric motor control module configured to control an electric motor based on a value of an electric motor torque control command, wherein: the motor control module stops the vehicle and maintains the stop state of the vehicle by the value of the second target torque as the value of the torque control command of the electric motor when the speed parameter becomes equal to or less than a predetermined value. 2. The control device for an electric motor vehicle according to claim 1, further comprising: a module for determining the moment immediately before stopping, configured to determine whether or not the vehicle will stop in the near future, while: the moment determination module just before stopping determines that the moment just before stopping has not been reached if the value of the first target torque exceeds the value of the second target torque, and determines that the vehicle will stop soon if the value of the second target torque exceeds the value first target torque. 3. The control device for an electric motor vehicle according to claim 1 or 2, further comprising: a module for evaluating disturbing torques, configured to evaluate disturbing torques, wherein: the second target torque value calculation unit calculates the target torque value as the second target torque value, the target torque value converging to the disturbing torque with decreasing speed parameter. 4. The control device for an electric motor vehicle according to claim 3, in which: the disturbing torque evaluation module evaluates the disturbing torque as a positive value on the road going uphill and a negative value on the road going downhill. 5. The control device for an electric motor vehicle according to claim 3, in which: the module for evaluating the disturbing torques resets the disturbing torque on a flat road. 6. The control device for an electric motor vehicle according to claim 3, in which: the first target torque value calculating unit calculates the target target torque value based on the vehicle information and calculates the first target torque value by correcting the calculated target target torque value based on the disturbing torque. 7. The control device for an electric motor vehicle according to claim 6, in which: the first target torque value calculating unit calculates the disturbance correction torque by multiplying the disturbing torque by a predetermined gain and calculates the value of the first target torque by summing the base value of the target torque and the disturbance correction torque. 8. The control device for an electric motor vehicle according to claim 7, in which: the first target torque value calculation unit calculates a disturbance correction torque by multiplying the product of the disturbing torque and a predetermined gain by a speed-based correction gain corresponding to the speed parameter; and speed-based correction gain is 1 if the speed parameter is less than the first predetermined value, 0 if the speed parameter exceeds the second predetermined value greater than the first predetermined value and equal to a value not less than 0 and not more than 1 and closer to 0 as the speed parameter increases, if the speed parameter is not less than the first predefined value and not more than the second predefined value. 9. A method for controlling an electric drive of an electric motor vehicle using an electric motor as a source of propulsion and configured to slow down by the regenerative braking force of an electric motor, the method comprising: the step of setting the value of the first target torque for driving based on the vehicle information as the value of the torque control command of the electric motor before the speed parameter proportional to the speed of the electric motor vehicle becomes equal to or less than the predetermined value, and setting the value the second target torque as the value of the torque control command of the electric motor when the speed parameter becomes p an apparent or less than the predetermined value; and a step in which the electric motor is controlled based on the value of the torque control command of the electric motor, wherein: in the step of controlling the electric motor, the vehicle is stopped, and the stopping state of the vehicle is maintained by the value of the second target torque as the value of the torque command of the electric motor when the speed parameter becomes equal to or less than a predetermined value. 10. A method of controlling an electric drive of an electric motor vehicle according to claim 9, wherein the method further comprises: the stage at which it is determined whether or not the vehicle will stop in the near future, while: at the determination stage, it is determined that the vehicle does not reach the moment immediately before stopping if the value of the first target torque exceeds the value of the second target torque, and it is determined that the vehicle will stop soon if the value of the second target torque exceeds the value of the first target torque. 11. A method of controlling an electric drive of an electric motor vehicle according to claim 9 or 10, further comprising: the stage at which the disturbing torque is evaluated, wherein: the value of the target torque is calculated as the value of the second target torque, and the value of the target torque converges to the disturbing torque with a decrease in the speed parameter. 12. The method of controlling an electric motor vehicle according to claim 11, in which: disturbing torque is estimated as a positive value on the road going uphill, and as a negative value on the road going downhill. 13. The method of controlling an electric motor vehicle according to claim 11, in which: disturbing torque is estimated to be zero on a flat road. 14. A method of controlling an electric motor vehicle according to claim 11, in which: the target torque reference value is calculated based on the vehicle information, and the first target torque value is calculated by correcting the calculated target torque value based on the disturbing torque. 15. The method of controlling an electric motor vehicle according to claim 14, in which: the disturbance correction torque is calculated by multiplying the disturbing torque by a predetermined gain, and the value of the first target torque is calculated by summing the base value of the target torque and the disturbance correction torque. 16. A method of controlling an electric motor vehicle according to claim 15, in which: the disturbance correction torque is calculated by multiplying the product of the disturbing torque and the predetermined gain by the correction gain based on the speed corresponding to the speed parameter; and speed-based correction gain is 1 if the speed parameter is less than the first predetermined value, 0 if the speed parameter exceeds the second predetermined value greater than the first predetermined value and equal to a value not less than 0 and not more than 1 and closer to 0 as the speed parameter increases, if the speed parameter is not less than the first predefined value and not more than the second predefined value.

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